Researchers say thousands of people have died prematurely as a result of the record-breaking wildfires that have swept America's west this autumn.
An unprecedented number of major fires have burned millions of acres in California, Oregon and Washington this year, throwing up choking smoke and sending air pollution across the country and beyond.
Researchers at Stanford University in California estimate there were between 1,200 and 3,000 excess deaths in California alone in one 40-day period in the late summer.
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